Cylindrical pressure vessel clamping device

ABSTRACT

A pressure clamp for connecting pressure vessel segments can include a pair of semi-circular sections, which can be placed around the ends of the segments, so that there is a slight gap between the semi-circular sections. The inner surfaces of the semi-circular sections can be formed with two notches with beveled surfaces. The beveled surfaces can engage corresponding slanted surfaces on the segment ends, to urge the segments towards each other as the clamp is tightened. A pair of jack screws can be threaded through the semi-circular sections so that the jack screws extend slightly outwardly from one of the sections and contact the other section at the beginning of the tightening process, to establish an initial assembly gap. As fasteners tighten the clamp around the segment, the jack screws can be backed out to maintain a uniformly decreasing assembly gap between the semi-circular sections.

FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT

The United States Government has ownership rights in this invention.Licensing inquiries may be directed to Office of Research and TechnicalApplications, Space and Naval Warfare Systems Center, Pacific, Code72120, San Diego, Calif., 92152; telephone (619) 553-5118; email:ssc_pac_t2@navy.mil, referencing NC 102238.

FIELD OF THE INVENTION

The present invention pertains generally to fastening systems. Moreparticularly, the present invention pertains to clamping devices thatcan be used to assemble components of a system that is under pressure.The present invention can be particularly, but not exclusively, usefulas a clamping device that provides a more reliable watertight sealbetween cylindrical pressure vessel body segments or end caps, whilealso allowing for easy assembly and disassembly of the segments/endcaps.

BACKGROUND OF THE INVENTION

Fastening systems for assembly components of an underwater vessel areknown in the prior art. Some of these aforementioned systems canincorporate a pair of hemispherical clamps, which can be used to mateadjacent body segments. The hemispherical clamps can extendapproximately 178 degrees around the circumference of the hull, and theclamps can be placed around a single O-ring and tightened to function asthe sealing mechanism for adjacent vessel segments.

But single O-ring type systems of the type described above can haveseveral disadvantages. First of all, these types of systems can besubject to single point failure, which could cause loss of investment ofthe contents of the vessel or the vessel itself. Additionally, the priorart systems can be challenging to install, as the two clamps do not meetface to face, but instead have a two degree gap between them foradjustment and tolerance variability. Installation is also made morechallenging because of their necessarily tight fit. Because of therequired tight fit, the clamps must be pressed on sometimes with thehelp of a mallet, which can make it very difficult to maintain symmetricgaps between front and back clamps.

Another issue with the aforementioned gap is the challenge ofmaintaining equal gap front and back as the screws are tightened.Consistency in the gap is needed for the mating fasteners to tightenproperly. If the gap is inconsistent, the clamp's mating fasteners maynot able to be torqued due to the gap and mirrored screw geometry. Whentightened, the screws fight each other for tension. With an uneven gap,as one screw is tightened the other loosens negating any torque value.This gap is also utilized during removal where a rod or screwdriver isinserted into the gap and struck with a mallet to force the clamps off.Both the clamps and the vessels can be damaged during the removalprocess.

One way to solve the above problems could be to use a standard Marmonclamp to mate the two adjacent segments. But Marmon clamps can alsoproduce additional disadvantages, such as non-compact design, difficultmating, and protruding features which could increase the hydrodynamicdraft of the overall vessel, and which could also snag objects along theoutside of a moving UUV (pressure vessel).

In view of the above, it is an object of the present invention toprovide a pressure vessel clamping device that allows for mating ofsegments in a manner which keep the outside diameter consistent alongits length, for increase hydrodynamic efficiency during deployment,operation and retrieval. Another object of the present invention is toprovide a pressure vessel clamping device that provides increased higherreliability of the watertight seal. Another object of the presentinvention is to provide a pressure vessel clamping device that providesfor a consistent gap forward and back to prevent uneven gap anditeration of assembly. Yet another object of the present invention toprovide a pressure vessel clamping device that maintains a consistentgap size during assembly, and which provides a resistance that allowsthe mating fasteners to be torqued during assembly. Still another objectof the present invention to provide a pressure vessel clamping devicethat can be easily and quick assembly and disassembly of pressure vesselsegments. Yet another object of the present invention to provide apressure vessel clamping device that allow for disengagement of theclamping device without damaging the device or the pressure vesselsegments. Another object of the present invention to provide a pressurevessel clamping device which can be easy to manufacture, and which canbe used in a cost-efficient manner.

SUMMARY OF THE INVENTION

A pressure clamp for connecting a first segment of a pressure vessel toa second segment of the vessel, and methods for use, can include a pairof semi-circular sections. The semi-circular section can be placedaround the end of the first segment and second segment, so that there isa slight assembly gap between the semi-circular sections, with theassembly gaps at both ends being substantially the same. The innersurfaces of the semi-circular section can be formed with a two notches,with each notch having a beveled surface. The beveled surface can definea decreasing distance between the beveled surfaces, from a maximumdistance at the inner surface of the semi-circular sections, which cantaper to a minimum distance proximate the outer surface of thesemi-circular sections. The beveled surfaces can engage a slantedsurface on the first segment end and the second segment end to urge thesegments towards each other as the clamp is tightened using fasteners.

The clamp and methods for use can also include a pair of jack screws.The jack screws can be threaded into one of the semi-circular section(at the ends) and threaded through until the jack screws extend slightlyoutwardly from one of the sections so that the jack screws contact theother sections at the beginning of the tightening process to establishthe assembly gap. As the fasteners tighten the clamp around the segment,the jack screws can be backed out to maintain a uniform gap between thesemi-circular sections as the clamp is tightened. Either of the segmentends can further be formed with at least two recesses. A correspondingO-ring can be placed into each recess, and O-rings can deform as saidsemi-circular section are tightened around the segments to establish awatertight seal.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the present invention will be best understood fromthe accompanying drawings, taken in conjunction with the accompanyingdescription, in which similarly-referenced characters refer tosimilarly-referenced parts, and in which:

FIG. 1 is an exploded side elevational view of the cylindrical pressurevessel clamping device of the present invention according to severalembodiments;

FIG. 2 is the same view as FIG. 1, when the device is assembled;

FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a greatly enlarged cross-sectional view taken along line 4-4in FIG. 3;

FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. 2;

FIG. 6 is a greatly enlarged cross-sectional view taken along line 6-6in FIG. 5, taken at the beginning of the clamp installation processaccording to some embodiments;

FIG. 7 is the same view as FIG. 4, taken at the beginning of the clampinstallation process according to several embodiments;

FIG. 8 is the same view as FIG. 7, taken at the end of the clampinstallation process;

FIG. 9 is the same view as FIG. 6, but taken at the end of the clampinstallation process; and,

FIG. 10 is a block diagram that is representative of steps that can betaken to practice the methods of the present invention according toseveral embodiments

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring initially to FIGS. 1-3, a cylindrical pressure vessel clampingdevice of the present invention according to several embodiments and isshown and is generally designated by reference character 10. As shown,device 10 can be used to connect the ends 12 a,b of a first segment 14and a second segment 16 The clamping device 10 can include a pair ofsemi-circular clamps 18 a, 18 b that can be placed around ends 12 a and12 b and secured with mating fasteners 20. The device 10 can alsoinclude at least two jack screws 22 a, 22 b, which can be threaded intocorresponding semi-circular clamps 18 a, 18 b, as the semi-circularclamps 18 a, 18 b are used to clamp ends 12 together. The manner inwhich the semi-circular clamps 18 cooperate with the ends 12, the matingfasteners 20 and the jack screws 22 to establish a watertight connectioncan be described more fully below.

The device 10 of the present invention according to several embodimentswas developed to provide a more reliable seal between the cylindricalpressure vessel body segments 14, 16, or between a segment 14, 16 or endcaps. End caps are not shown in the Figures. However, it should beappreciated that an end cap can be substituted for either segment 14 or16, or any segment for the vessel, provided the end cap has thecorresponding structure at its end 12 to engage the semi-circular clamps18 (either the structure of end 12 a or of 12 b, as described more fullybelow).

The device 10 of the present invention is an improvement over existingdesigns, in that it can allow for easy assembly and disassembly of thedevice. More specifically, the clamps in the prior art can bechallenging to install as they do not meet face to face but instead havea slight gap between the semi-circular clamps, which can allow foradjustment and tolerance variability. But the gap for the prior artdevice can make installation more challenging because of theirnecessarily tight fit. The semi-circular clamps often must be pressed on(sometimes with the help of a mallet) and therefore are very difficultto maintain symmetric gaps between front and back clamps. Another issuewith the aforementioned gap is the challenge of maintaining equal gapfront and back as the screws are tightened. Consistency in the gap isneeded for the mating fasteners to tighten properly. Additionally, theclamp's mating fasteners are not able to be torqued due to this gap andmirrored screw geometry. When tightened, the screws fight each other fortension. Therefore, as one screw is tightened the other loosens negatingany torque value.

This slight gap for the clamps in the prior art has also been usedduring removal of the prior art clamps from the vessel. Moreparticularly, a rod/screwdriver or similar structure has often beenjammed into the gap and pounded on with a hammer or mallet to force theclamps off, because the clamps themselves do not have features forself-extraction. As a result, the prior art clamps can often becomedamaged in the process of removal. The underwater pressure vesselclamping device of the present invention can add a jack screw 22 featureand other structure as described below, to avoid these disadvantages.Additionally, and as can be seen in FIGS. 2 and 3, the device 10 of thepresent invention can result in pressure vessel (once segments 14 and 16are assembled), with a streamlined, hydrodynamic configuration, over theprior art clamps, which can have protrusions that can decrease thehydrodynamic efficiency of the assembled vessel, and that can get caughtor snagged on kelp, trash, or other underwater items, or the oceanfloor.

Referring now to FIG. 4, the structure of the semi-circular clamps 18and ends 12 a, 12 b can be seen in greater detail. As shown,semi-circular clamps 18 can include at least two notches 24, 26, whichcan be formed in the clamp by means known in the art, such as milling,machining, etc. Each notch 24, 26 can be formed with at least onebeveled surface 28, 30 as shown in FIG. 4. The beveling of beveledsurface 28, 30 can result in notches where can have a minimum distanced₁ between the beveled surfaces 28, 30 proximate outer surface 32 ofclamp 18. The minimum distance d₁ can have an increasing taper orgradient to a maximum distance d₂ between beveled surfaces 28, 30 at theinner surface 34 of clamp 18.

As shown in FIGS. 4 and 7-8, the structure of the ends 12 can be adaptedto facilitate mating of segments 14 and 16. More specifically, ends 12 aand 12 b can be formed with respective grooves 37, 39. Grooves 37, 39can each be formed with a respective slanted surface 38, 40. Slantedsurfaces 38 and 40 can engage respective beveled surfaces 28 and 30 whensemi-circular clamps are placed around end 12 a and 12 b and tightened.End 12 a can be formed with an inclined surface 46 (Please see FIGS. 7and 8), and end 12 b can further be formed with at least two recesses35, and O-rings 36 can be placed into each corresponding recess 35. Itshould be appreciated that the number of recesses 35 and O-rings 36 inend 12 b, as well as the O-ring durometer, can be chosen according tothe desired design depth of the vessel segments. Additionally, therecesses 35 could also be formed in end 12 a vice 12 b without departingfrom the scope of the present invention, as long as the O-rings 36becomes deformed during tightening on the semi-circular clamps 18, toestablish the watertight seal for segments 14, 16. Stated differently,the recesses can be on either end 12 a, 12 b, provided the inclinedsurface 46 is on the other of ends 12 a, 12 b to cause deformation ofthe O-rings during operation of the device 10 to assemble segments 14and 16.

As shown in FIGS. 5 and 6, a pair of jack screws 22 can be threaded intosemi-circular clamps 18 a and 18 b. The jack screws 22 can allow fortorqueing of the mating fasteners 20 during installation of the deviceon the first and second segments 14, 16. The jack screws 22 can alsoprovide a simple, integrated way to remove the clamps, and further allowfor a consistent assembly gap 42 at both ends of clamps 18 a, 18 bduring assembly, as described below. More specifically, as the clampsare tightened the O-rings are brought together and sealed, duringassembly and use, the jack-screws provide a base to torque against oncethe rings are sealed.

For installation of the device 10, and referring now to FIGS. 5-9, theO-rings 36 can be greased and can then be placed in correspondingrecesses 36. Segments 14 and 16 can be placed end 12 a to end 12 b, andheld in position as the clamps 18 are added by placing clamps 18 a, 18 baround ends 12 a, 12 b. At this time the jack screws 22 can be threadedinto clamps 18. Each jack screw 22 can be threaded through one ofsemi-circular clamps 18 a, 18 b until it contacts the other of clamps 18a, and 18 b. This can establish a first configuration, wherein there isa uniform assembly gap 42 at both interfaces (ends) of semi-circularclamps 18 a, 18 b, as shown in FIGS. 5 and 6.

Once the jack screws 22 are threaded as describe above, the matingfasteners 20 can be tightened and torqued. To do this, each jack screw22 can be backed out slightly, or unscrewed, the same amount. Next, themating fasteners 20 can be tightened until the jack screws 22 againcontact the clamps 18 (but with a smaller assembly gap 42). Once theslightly back-out jack screws 22 again contact the semi-circular clamps,the jack screws 22 can again provide the resistance, which can allow themating fasteners 20 to be torqued to their predetermined design limit,the jack screws can be threaded out by a couple of threads. The matingfasteners can then be tightened again until the design torque for themating fasteners is reached again. It should also be appreciated that inseveral embodiments, mating fasteners such as socket head cap screws canbe used to fasten clamps 18 to each other. Once such mating fastener ofthis type that could be used is the Type 316 Stainless Steel Socket HeadCap Screw, available from McMaster-Carr®. For these embodiments, themating fasteners can be made “captive” by threading the through holes onboth clamps 18 a, 18 b, so that there is a small length of thread whichcan make the mating fastener captive after the initial thread through.

The above process can be repeated. As this occurs, the assembly gap 42becomes smaller and the semi-circular clamps 18 can become tightenedaround ends 12. The entire process can be repeated until the desiredassembly gap 42 is reached (at this point the device 10 can have asecond configuration, wherein assembly gap 42 is at a minimum, as shownin FIG. 9), or in other embodiments the process can be repeated until asecond configuration is reached wherein assembly gap 42 is completelyclosed and semi-circular clamps 18 contact each other at the ends of theclamps 18 (for the embodiments without a gap, sing clamps 18 a and 18 bcontact each other, the mating fasteners can be torqued without jackscrew 22). From, the above, it should be appreciated that the jackscrews 22 greatly facilitate the assembly of the device by maintain auniform assembly gap 42 between the ends of the semi-circular clamps 18during tightening of the clamps. The added benefit of having thejackscrew in place is to avoid fouling during use.

As the semi-circular clamps 18 are tightened with mating fasteners 20,the beveled surfaces 28, 30 of the clamps can engage the correspondingslanted surface 38, 40 of respective segment ends 12 a, 12 b. As thisoccurs, the engagement of beveled surfaces 28, 30 with slanted surfaces38, 40 can cause ends 12 a and 12 b to be urged towards each other, inthe direction indicated by arrows 44 in FIG. 7. As this occurs, theinclined surface 46 of end 12 a moves toward recesses 35 until inclinedsurface 46 of end 12 a contacts end 12 b. Once this occurs, the O-rings36 can become deformed within recesses 35 to thereby aid in theformation of a watertight seal for segments 14 and 16.

For removal of the semi-circular clamps 18 and disassembly of segments14, 16, the mating fasteners 20 can be loosened and the jack screws 22can be tightened to establish a leveraging action, which pries thesemi-circular clamps 18 a and 18 b apart. Damage to the clamps andunnecessary damage of sensitive internal components can be avoided ifjack screws are used instead of a prior art mallet and screwdriver toremove the clamps. In some embodiments of the invention, the jack screwscan be removed and the mating fasteners 20 can be loosened so that thereare just a couple threads into the opposing clamp and are loose butstill captured and holding the clamps from falling out of the clamps 18.Then, longer versions of the jack screws can be added and tightenedturning about half a turn in sequence and repeated until the matingfasteners bottom out or the clamps become loose. For embodiments wheresocket head cap screws are used as mating fasteners, the fasteners canbe loosened, but since they are captive because of the structuredisclosed above, they do not fall out once the clamps 18 a, and 18 b aredisconnected. Thus, the self-extraction features of the device 10 of thepresent invention according to several embodiments can become apparent.

By cross-referencing FIGS. 6 and 9, it can be seen that in severalembodiments, the jack screws 22 can have a chosen length thatestablishes the maximum assembly gap 42 when the jack screw is threadedall the way into clamp 18 (FIG. 6). At the same time, the jack screwlength can be chosen so that when the clamp is fully installed andassembly gap 42 is at a minimum (FIG. 9), the jack screw does not extendpast outer surface 32 of clamps 18, to thereby maintain the hydrodynamicprofile of the vessel. For these embodiments, the jack screws can remainin place after installation of the device. In still other embodiments,the jack screws can be removed and a plug (not shown) can be threadedinto the threaded clamp opening which receives the jack screw, toprevent fouling of the threaded opening. For disassembly, the plug canbe removed and the jack screws 22 can be reinserted to accomplish thedisassembly. In still other embodiments, such as in cases of extremefouling, for instance, a longer jack screw 22 than the installation jackscrew 22 can be used to accomplish the prying action to force clamps 18a and 18 b apart for disassembly.

Referring now to FIG. 10, the methods of the present invention accordingto several embodiments can be depicted using the block diagram, which isdesignated using reference character 50. As shown, the methods caninclude the initial step of providing semi-circular clamps 18, as shownby box 52. Next, the methods can include the steps of forming notches24, 26 in the clamps 18 as shown by box 54, and beveling the notches toestablish a respective beveled surface 28, 30 for each notch 24,26, asshown by box 56. As shown by step 57, the methods can include the stepof prepping the end 12 a and 12 b and segments 14 and 16. For thisspecification, what is meant by prepping the ends 12 is establishing therecesses 35, O-rings 36, inclined surface 46 and slanted surfaces 38, 40structure for the ends 12, as described above.

Next, and as also shown by box 58, the methods can include the step ofplacing the semi-circular clamps 18 around the ends 12 of segments 14,16 and attaching the clamps to each other. To do this, the jack screws22 can be threaded into the clamps 18 (as depicted by box 60) until theinitial assembly gap 42 is established. The jack screws 22 can beselectively backed out as shown by box 62 and the mating fasteners canbe torqued, as shown by box 64 and the mating fastener 20 can again betorqued. Steps 62 and 64 can be repeated until the inclined surface 46,recess 35 and O-ring structure of ends 12 have cooperated to establishthe watertight structure for segments 14, 16, and/or until assembly gap42 has vanished and semi-circular clamps 18 contact each other at theends of the clamps 18. For disassembly, the mating fasteners can beloosened and the jack screws 22 can be threaded into the clamps 18 asdescribed above, to accomplish disassembly of the device 10 withoutstriking the device with a mallet or similar tool.

The use of the terms “a” and “an” and “the” and similar references inthe context of describing the invention (especially in the context ofthe following claims) is to be construed to cover both the singular andthe plural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

What is claimed is:
 1. A pressure clamp comprising: a first segment of avessel; a second segment of said vessel; a first semi-circular section;a second semi-circular section; wherein said first segment has a firstsegment end and said second segment has a second segment end; whereinsaid first segment end and said second segment end are formed with arespective first and second grooves, said first and second grooveshaving respective slanted surfaces; at least two mating fasteners forfastening said first semi-circular section to said second semi-circularsection; said first semi-circular section and said second semi-circularsection being configured to be placed around said first segment end andsaid second segment end; each of said first semi-circular section andsaid second semi-circular section having an outer surface and an innersurface, said first semi-circular section's inner surface and secondsemi-circular section's inner surface being formed with respective firstand second beveled surfaces; and, said first beveled surface engagingsaid first slanted surface in said groove and said second beveledsurface engaging said second slanted surface in said groove to urge saidfirst segment towards said second segment when said clamp is tightenedusing said mating fasteners, wherein said second segment end is furtherformed with a pair of stepped recesses, and said clamp further comprisesa pair of corresponding O-rings, were one O-ring is placed into eachcorresponding said recesses, said O-rings deforming to take the shape ofsaid recesses as said clamp is tightened around the first segment andthe second segment to form a watertight seal for said first segment andsaid second segment when said clamp is in said second configuration,wherein said second segment end between said pair of stepped recessesand said second groove is a third groove and said second semi-circularsection has a projection that has a shape corresponding to said thirdgroove which said projection penetrates, wherein said first segment endhas a tapered surface that covers and abuts the pair of steppedrecesses.
 2. The clamp of claim 1, further comprising: a first jackscrew; a second jack screw; said first jack screw configured to beinserted into said first semi-circular section and threaded throughuntil it extends outwardly therefrom and contacts said secondsemi-circular section to establish a first assembly gap; and, saidsecond jack screw configured to be inserted into said secondsemi-circular section and threaded therethrough until it contacts saidfirst semi-circular section to establish a second assembly gap; and,said first assembly gap being substantially equal to said secondassembly gap.
 3. The clamp of claim 2, wherein said clamp has a firstconfiguration comprising a maximum said first assembly gap and a maximumsaid second assembly gap, and a second configuration comprising aminimum said first assembly gap and a minimum said second assembly gap.